Interfacial exchange of airflow and bacteria-carrying particles induced by door opening and foot traffic in an operating room

Abstract

Maintaining high air cleanliness in operating rooms (ORs) can reduce surgical site infections (SSIs). However, door openings and foot traffic during surgery may allow the intrusion of contaminated air and increase microbial contamination in ORs. In this study, numerical methods were applied to investigate the dynamic airflow and bacteria-carrying particle (BCP) dispersion during sliding door opening and foot traffic in an OR. The door movement and realistic human walking were modeled by the dynamic mesh technique. The interfacial exchange of airflow and BCPs was evaluated as the medical staff entered and exited the OR under fixed supply air temperatures and various differential pressures, respectively. Results showed that walking across the door interface caused a sharp increase in airflow exchange between the OR and the anteroom (ANT). An average walking speed of 1.2 m/s induced a maximum inflow rate of approximately 1.32 times greater when entering the OR than when leaving the OR. Once the door was open, the temperature difference convection effect was more significant than the pressure difference outflow effect. Differential pressure outflow indirectly affected airflow exchange at the door interface by changing the direction and temperature of airflow in the ANT. Whether entering or leaving the OR, the BCP intrusion ratios were on average 1.5 times higher at high pressure differentials (15 and 20 Pa) than at low pressure differentials (5 Pa and 10 Pa). This study is expected to improve the understanding of the impact of door opening and foot traffic on OR air quality during surgery.